1. Field of the Invention
The present invention relates to a structure for connecting a window glass antenna with a feeder, and more particularly to a structure for respectively connecting primary and secondary antennas with an inner conductor of a coaxial cable serving as the feeder and with an outer conductor of the same.
2. Description of the Prior Art
There are some proposals of providing an antenna for transmission and reception of ultrashort waves on an automobile or a building window glass. For example, U.S. Pat. No. 4,721,964 discloses a vehicular window glass antenna system which has one feeding point connected to an inner conductor of a coaxial cable is grounded, through a lead such as a polyvinyl chloride wire, to a part of a vehicular body serving as a grounded conductor, the part being located near the feeding point. However, this type of antenna has the following drawbacks.
The outer conductor is not directly connected to the part of the vehicular body, but to the same through the lead. Therefore, the assembly work becomes complicated due to the installation of the lead. Furthermore, due to the provision of the lead, there is provided a certain inevitable transmission loss, thereby lowering reception gain.
JP-B (Utility Model) 51-16677 discloses a vehicular window glass antenna which is installed on a laminated glass. The laminated glass has two overlapped glass plates interposing therebetween an interlayer and an antenna. One of the glass plates has a through opening for fully receiving therein a first terminal connected to the antenna. The first terminal is detachably connectable with a second terminal of a feeder. However, this type of antenna has the following drawback.
For installing the first terminal, it is necessary to drill the glass plate. This makes the assembly complicated and lowers strength of the laminated glass. Furthermore, this type of antenna can not be installed on a single glass plate.
JP-A (Patent) 61-210705 discloses a space diversity reception system installed in an automobile. The system includes a plurality of antennas spaced from each other with a certain distance therebetween for minimizing the effects of fading. However, this system has the following drawback.
Each antenna is connected to a coaxial cable through two terminals. Thus, by increasing the number of terminals, the assembly work becomes more complicated and the external appearance of the system becomes worse.
JP-A (Utility Model) 4-5708 discloses a structure for connecting primary and secondary antennas with an inner conductor of a coaxial cable and with an outer conductor of the same through first and second terminals, respectively. The first terminal has a bent portion defining a space for tightly holding therein the inner conductor. The second terminal has a supporting portion which is semi-cylindrical in shape, and on which the outer conductor is supported. However, this connecting structure has the following drawbacks.
Because the second terminal has only one portion for supporting the coaxial cable, the coaxial cable can not be supported by the second terminal with a sufficient strength. Because an upper half portion of an end portion of the outer conductor is exposed, upon soldering the outer conductor to the second terminal by a soldering iron, the outer conductor tends to be overheated by a direct abutment with the soldering iron. This overheat tends to damage an insulator disposed between the inner and outer conductors.